Normal Ultrasound Parameters during the First Trimester |
|
|
Ultrasound Sign |
Embryo |
Cardiac motion in embryos ³5mm. |
Yolk sac |
Yolk sac <6 mm Round or spherical Bright echogenic rim and internal anechoic area |
Amnion |
Embryo always visualized when amnion is visible |
Amniotic fluid |
Mean diameter of amniotic cavity is ±10% greater than length of embryo |
Gestational sac |
³13mm – yolk sac
should be visualized |
Trophoblastic |
Regular. |
Sac growth |
Greater than 0.6mm/day. |
bhCG
correlation |
Direct correlation between sac size and bhCG levels. |